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Biomedical subjects

L J Murphy

Publications and source records attributed to L J Murphy.

At least 145 records · Page 8Linked to original sources
PubMed1987

Regulation of 70-kilodalton heat-shock-like messenger ribonucleic acid in vitro and in vivo by prolactin.

A cDNA clone, pNb29, was isolated from a library made from mRNA of Nb2 rat lymphoma cells stimulated by PRL. The nucleotide sequence of pNb29 was found to be identical to the 70-kilodalton heat-shock-like (hsp-70-like) mRNA. The levels of this mRNA increased 8 +/- 3-fold after PRL stimulation of arrested Nb2 cells, and is expressed in different amounts in the normal rat tissues analyzed. To determine whether hsp-70-like mRNA was PRL responsive in vivo, ovine PRL was administered to hypophysectomized rats. A 5 +/- 2-fold increase in hepatic hsp-70-like mRNA was observed 9 h after injection. Thus PRL appears to regulate a heat-shock-like mRNA both in vitro and in vivo. This novel finding extends the already wide range of biological effects ascribed to PRL.

Animals↗
PubMed1987

Estrogen induces insulin-like growth factor-I expression in the rat uterus.

The inability to convincingly demonstrate a mitogenic effect of estrogen on isolated uterine cells in culture suggests that autocrine or paracrine growth factors may be important in the estrogen-induced uterine proliferative response. Here we report that uterine expression of insulin-like growth factor-I (IGF-I), an important mediator of GH action, is increased after 17 beta-estradiol (5 micrograms/100 g bw, ip) administration to ovariectomized prepubertal rats. An increase in uterine IGF-I mRNA abundance, approximately 14-fold above untreated controls, was apparent 6 h after estrogen administration and the level achieved exceeded that seen in the uterus from intact mature rats during diestrus. In contrast to the increase in IGF-I expression in the uterus, no significant change in serum IGF-I concentration or hepatic or renal IGF-I mRNA abundance was demonstrable after 17 beta-estradiol injection of ovariectomized prepubertal rats. The increase in uterine IGF-I expression, was similar in both pituitary-intact and hypophysectomized, ovariectomized rats. We believe this is the first report of induction of IGF-I expression by estrogen in vivo. As such, the finding expands the role and significance of IGF-I as a mediator of growth beyond that related to GH.

Animals↗
PubMed1987

Sir Douglas Shields (1876-1952): a forgotten Australian surgeon.

The remarkable and colourful career of Sir Douglas Shields of Melbourne is unparalleled among Australian surgeons of his generation: Murray Morton describes it as a romance. He graduated in 1897 and was, in turn, a country general practitioner, the principal medical officer of an overcrowded plague-ship bringing home soldiers from the Boer War, senior surgeon of St Vincent's Hospital, Melbourne then, in London, surgeon-in-chief of his own hospital converted to the 'Hospital for Wounded Officers' with promotion to the ranks of brigadier-general and rear-admiral, then knighted and, finally, a consultant surgeon with private hospitals in Park Lane and in Cannes, and with patients largely drawn from the aristocracy, the rich and the famous. His name is now virtually forgotten in Australia but, for many years after he left Melbourne in 1912, stories used to be told about his career and experiences, many of which had little basis in fact, and even the two brief biographical accounts of his career by Murray Morton and Ormond Smith contradict each other. This paper will, I hope, help to preserve the memory of Sir Douglas Shields whom Ormond Smith considered 'one of the brightest ornaments of the Medical School of the Melbourne University'.

Australia↗
PubMed1986

Modulation of lactogenic receptors by progestins in cultured human breast cancer cells.

Progesterone receptors (PgR) are present in many breast cancers, but few specific actions of progestins in breast cancer cells have been reported. We now report that progestins specifically modulate lactogenic receptor expression in cultured T-47D and MCF-7 human mammary carcinoma cells. When T-47D cells were preincubated for 24 h with 1 nM medroxyprogesterone acetate (17 alpha-acetoxy-6 alpha-methyl-4-pregnene-3,20-dione), specific binding of [125I]human GH ([125I]hGH) and [125I]human PRL was increased to 205 +/- 22% (+/- SE) (P less than 0.01) and 175 +/- 32% (P less than 0.05), respectively, of that in control cultures. There was no significant effect on cell number and no significant enhancement of specific binding of [125I]porcine insulin, [125I]salmon calcitonin, [125I]human transferrin, or [3H] Concanavalin A. Lactogenic receptor number was increased from 6,490 +/- 500 (n = 12) to 13,180 +/- 3,270 (n = 7; P less than 0.01) sites/cell, with no significant change in affinity for hGH. Progesterone, which is readily metabolized by these cells, was less potent than the synthetic progestins (medroxyprogesterone acetate, R 5020 (17 alpha, 21-dimethyl-19-norpregn-4,9-diene-3,20-dione), and ORG 2058 (16 alpha-ethyl-21-hydroxy-19-norpregn-4-en-3,20-dione), but physiological concentrations of progesterone (1 nM) significantly enhanced specific binding of [125I]hGH to 153 +/- 23% of the control value (n = 6; P less than 0.05). Physiological concentrations of androgens, estrogens, and glucocorticoids had no significant effect. MCF-7 cells were considerably less sensitive to these effects of progestins than T-47D cells, probably due to the lower PgR concentration in MCF-7 cells. These observations, which indicate that lactogenic receptor expression is controlled, at least in part, by progestins in these mammary carcinoma cell lines, may have important implications in the management of human breast cancer, where high levels of this receptor may reflect a functional PgR and a highly hormone-dependent phenotype.

Breast Neoplasms↗
PubMed1986

Progestin regulation of epidermal growth factor receptor in human mammary carcinoma cells.

Epidermal growth factor (EGF) receptors are present in human breast cancer and probably mediate the effects of EGF and the autocrine effects of alpha-transforming growth factors, produced by breast cancer cells. Steroid hormones influence the growth of some human cancers, and both direct and indirect effects on cell proliferation have been proposed. One potential indirect effect of steroids would be to augment sensitivity to other endocrine and autocrine factors by up-regulation of their receptors. We therefore investigated the effects of various steroids on EGF receptor expression in T-47D, MCF-7, and BT 20 human mammary carcinoma cells in culture. Preincubation of T-47D cells for 24 h with a series of androgens, estrogens, glucocorticoids, and progestins resulted in a significant enhancement of specific 125I-EGF binding in the presence of progestins only. Increased binding of EGF was associated with neither a change in cell number nor changes in the specific binding of concanavalin A, insulin, or calcitonin but was accompanied by an increase in lactogenic receptor expression. When assayed at 20 degrees C, increased EGF binding was due to an increase in receptor number (33,380 +/- 7,410 sites/cell in control cultures; 67,460 +/- 20,330 sites/cell in cultures treated with 1 nM medroxyprogesterone acetate for 24 h; P less than 0.05) without a change in receptor affinity. Two- to 3-fold increases in receptor number were also apparent when binding was measured at 4 degrees C, indicating that the effect was due to an increase in expression of receptor at the cell surface rather than progestin effects on internalization and degradation. These data illustrate that the expression of EGF receptor in some breast cancer cells is regulated in part by mechanisms mediated via the progesterone receptor, since the effect was confined to progestins, potency among a series of progestins was correlated with their affinities for progesterone receptor, and sensitivity among the three cell lines studied was related to the presence and concentration of cellular progesterone receptor.

Androgens↗
PubMed1985

Regulation of growth hormone and epidermal growth factor receptors by progestins in breast cancer cells.

A 24 hr incubation of T-47D human breast cancer cells with R5020, a synthetic progestin, resulted in a 200-250% increase in the specific binding of human growth hormone (hGH) and epidermal growth factor (EGF) by these cells. This effect was specific for progestins in that similar responses were observed with progesterone, medroxyprogesterone acetate and ORG 2058 but no significant increases in hGH or EGF binding were observed in cells incubated with testosterone, estradiol or hydrocortisone. Increased binding was due to an increase in the concentration of receptors (hGH, control = 6,490 +/- 500, progestin treated = 13,180 +/- 3,270 sites/cell; EGF, control = 33,380 +/- 7,410, progestin treated = 67,460 +/- 20,330 sites/cell) while the affinity constants for the hormone-receptor interactions were unchanged by progestin treatment. The specific binding of insulin, calcitonin, transferrin and concanavalin A was unaffected by these treatments. It is concluded that expression of hGH and EGF receptors in this breast cancer cell line is regulated by progestins.

Breast Neoplasms↗
PubMed1985

Human growth hormone induces and maintains c-myc gene expression in Nb2 lymphoma cells.

The effect of human GH (hGH) on c-myc gene expression and cell proliferation in the Nb2 lymphoma cell line was examined. The addition of hormone to stationary cultures of Nb2 cells resulted in an increased accumulation of c-myc transcripts that was detectable within 15 min, reached a maximum induction of 25-fold in 3 h, and then gradually declined. Although maximal accumulation of c-myc transcripts occurred within 3 h after hGH addition, removal of the hormone even after 4 h of treatment resulted in a failure of the cells to proliferate. This loss of proliferative capacity following hormone removal was accompanied by a 20-fold reduction in the level of c-myc transcripts. These results indicate that hGH induced proliferation of Nb2 cells is associated with the induction and maintenance of c-myc gene expression.

Cell Division↗
PubMed1984

Effects of hypophysectomy and subsequent growth hormone replacement in the rat on the ability of serum to stimulate proliferation of human and mouse (BALB/c 3T3) fibroblasts.

The ability of cultured human fibroblasts to synthesize and secrete a mitogenic, somatomedin C-like peptide suggests that human fibroblasts unlike certain other cell lines may not require exogenous somatomedin for cell proliferation. The aim of this study was to examine the effects of hypophysectomy and subsequent growth hormone (GH) replacement on the ability of rat serum to stimulate proliferation and DNA synthesis in cultured human fetal skin fibroblasts. For comparison we have also examined the effects of serum from hypophysectomized (hypox) and GH-replaced hypox rats on mouse BALB/c 3T3 fibroblasts, a cell line which has been shown to require exogenous somatomedin (SM) for DNA synthesis and cell proliferation. Human fibroblast proliferation and DNA synthesis (measured as thymidine incorporation) were significantly enhanced (P less than 0.025) when these cells were cultured in low concentrations of hypox rat serum compared to normal rat serum. When thymidine incorporation into DNA was expressed in terms of a normal rat serum pool (arbitrarily assigned a potency of 1 unit/ml), serum from hypox rats was significantly more potent than serum from normal rats (1.52 +/- 0.16 (SEM) vs. 0.99 +/- 0.10 units/ml, P less than 0.0125). Replacement treatment of hypox rats with human GH, 0.2 IU/100 g body weight/day or 0.4 IU/100 g body weight/day decreased the potency of the rat serum in terms of stimulation of thymidine incorporation from 1.52 +/- 0.16 to 1.30 +/- 0.14 and 1.08 +/- 0.06 units/ml respectively. In contrast serum from untreated hypox rats was significantly less potent than normal rat serum in stimulating BALB/c 3T3 DNA synthesis (0.36 +/- 0.06 vs. 1.04 +/- 0.16 units/ml, P less than 0.0025).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Harry Harris and his contribution to suprapubic prostatectomy.

In 1928 Harry Harris of Sydney published an account of his new operation "Prostatectomy with complete closure" (J. Coll. Surg. Aust. 1, 65-7, 1928), in which he reported a degree of success unsurpassed in the world. This 'Harris prostatectomy' was a technique of precision, planned to achieve primary closure of the bladder as a routine procedure. This operation was ignored at the time but during the late 1930s it gained Harris a world-wide reputation and was widely adopted in Britain, in Europe and in Australasia. The procedure then largely fell into disuse for reasons which will be discussed later. The place of this operation in the history of prostatectomy is fading from memory, and Harris' name is in danger of being forgotten, as Maurice Ewing (Aust. N.Z.J. Surg. 47, 531-6, 1977) pointed out in his Harry Harris Memorial Oration in 1969.

Australia↗
PubMed1984

The mouse fibroblast growth hormone receptor: ligand processing and receptor modulation and turnover.

The recent observation that adipose conversion of mouse 3T3 fibroblasts is stimulated by physiological concentrations of human GH (hGH) and rat GH in vitro suggested that this cell line may be suitable for the study of GH-receptor interactions. The aim of this study was to examine the binding and subsequent processing of [125I]iodo-hGH by BALB/c 3T3 mouse fibroblasts. Binding of [125I]iodo-hGH to 3T3 fibroblasts was time and temperature dependent. Apparent steady state binding was achieved after 1 and 2 h at 37 and 30 C, respectively. At 37, 30, and 20 C specifically bound [125I]iodo-hGH became increasingly resistant to removal by acid treatment (0.15 M NaCl/0.05 M glycine, pH 2.5). In contrast at 4 C or at higher temperatures in the presence of metabolic inhibitors, a greater proportion of specifically bound hGH was removed by acid treatment. Inclusion of 0.2 mM chloroquine in the incubation medium resulted in significantly more accumulation of trichloroacetic acid (TCA)-precipitable radioactivity compared to control cells without affecting the shift of radioactivity from the acid-elutable to the acid-inaccessible compartment. After removal of [125I]iodo-hGH from the medium there was a rapid loss of radioactivity (t 1/2 = 36.5 +/- 7.2 min, SE, n = 3) from the cell monolayer with a concomitant appearance in the medium of TCA-soluble radioactive species. Chloroquine reduced the rate of efflux of radioactivity from the monolayer (t 1/2 = 4.5 +/- 0.6 h, n = 3) and the appearance of TCA-soluble material in the medium. The half-time of GH receptor loss after inhibition of protein synthesis with cycloheximide (0.1 mM) was 1.25 +/- 0.14 h, n = 3). In contrast half-time of net receptor synthesis calculated from the recovery of specific [125I]iodo-hGH binding capacity after ligand-induced down-regulation was 10.2 +/- 1.5 h, n = 3). These data reveal that after binding of [125I]iodo-hGH to specific cell surface receptors there is rapid irreversible binding of GH to its receptor with a resultant reduction in receptor concentration. Degradation of [125I]iodo-hGH occurs intracellularly and involves processes which are inhibited by lysosomotropic agents. On the basis of these studies we conclude that the binding and subsequent processing of GH by 3T3 fibroblasts is qualitatively similar to that described for other polypeptide hormones and growth factors in this and other cell lines.

Animals↗
PubMed1984

Growth hormone binding to cultured human breast cancer cells.

The role of pituitary hormones in the pathogenesis of human breast cancer is unclear, although hypophysectomy is of therapeutic benefit in some patients with advanced breast cancer. Agents that lower serum PRL are of little value in the treatment of breast cancer, suggesting that other pituitary hormones may be important in the control of the growth of human breast cancer in vivo. Since human (h) GH is lactogenic in rodents, we investigated the binding of [125I]hGH and [125I]hPRL to the cultured human breast cancer cell lines T-47D and MCF-7. Both [125I]hGH and [125I]hPRL bound to a saturable binding site with high affinity (Ka = 0.94-1.70 X 10(9) M-1) and low capacity (4140-6560 sites/cells) in the two cell types. hGH and hPRL were mutually competitive, indicating that both hormones bound to the same receptor site. After binding of [125I]hGH to cell monolayers, the hormone was rapidly internalized in a time-, temperature-, and energy-dependent fashion. Lysosomotropic agents inhibited degradation of [125I]hGH and enhanced specific binding. Preincubation of MCF-7 cells with either hGH or hPRL resulted in loss of hGH/hPRL-binding sites, although hGH was consistently more potent in inducing down-regulation of the receptor. On the basis of these observations we suggest that hGH is a potent ligand for the lactogenic receptor in human breast cancer cells in vitro and may be important in the pathogenesis, growth, and metastasis of human breast cancer.

Aged↗
PubMed1984

Correlation of lactogenic receptor concentration in human breast cancer with estrogen receptor concentration.

The presence of receptors for lactogenic hormones in human breast cancer tissue has been documented previously, but the relationship between the expression of these receptors and estrogen receptor (ER) status has not been adequately studied. In this report, the specificity of 125I-human growth hormone (HGH) binding in both cultured human breast cancer cell lines and tumor biopsies was studied to establish that HGH was a suitable ligand for investigating lactogenic receptor concentration in these tissues. In addition, the relationship between specific binding of 125I-HGH and ER concentration in human breast cancer was investigated. Specific 125I-HGH binding to 14 breast cancer cell lines in long term culture and to membrane preparations (microsomal and plasma membrane fractions) from 31 breast cancer biopsy specimens was examined. Human prolactin and HGH were approximately equipotent in inhibiting binding of 125I-HGH to both cultured breast cancer cell lines and to membrane preparations from breast cancer biopsy specimens. Competitive inhibition experiments using lactogenic and somatogenic hormones established that the specificity of 125I-HGH binding to breast cancer biopsy material was similar to that of cultured breast cancer cell lines and similar to that reported for subprimate lactogenic receptors. Saturable, high-affinity (Ka = 0.53 to 2.33 nM-1), low-capacity (330 to 6560 sites/cell) growth hormone binding sites were found on each of the ER-positive cell lines, whereas no specific 125I-HGH binding to ER-negative cell monolayers was detected. When all cell lines were considered, a significant linear correlation (r = 0.745, p less than 0.001) between ER and lactogenic receptor concentrations was found. Significant specific 125I-HGH binding, greater than 1% of the total radioactivity added, was detected in 20 of 31 (65%) breast tumor biopsy specimens. The mean affinity and capacity of the lactogenic receptor as measured in 8 separate membrane preparations were Ka = 0.52 +/- 0.09 (S.E.) nM-1 and 255 +/- 85 fmol/mg protein. Membrane preparations from ER-negative tumors (less than 3 fmol ER/mg cytosol protein) bound significantly less 125I-HGH than did membrane preparations from ER-positive tumor biopsies (1.22 +/- 0.44 versus 3.21 +/- 0.56%, p less than 0.05). A significant linear correlation between specifically bound 125I-HGH and ER concentration (r = 0.412, p less than 0.02) was demonstrated in the 31 breast cancer biopsy specimens studied.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding, Competitive↗
PubMed1983

Acute changes in thyroid function tests following ingestion of thyroxine.

The timing of blood sample collection in relation to ingestion of thyroxine has been thought to be of no consequence in the assessment of patients receiving thyroxine medication. We have investigated changes in serum thyroid hormones after oral ingestion of thyroxine. Therapeutic doses of thyroxine (100-300 micrograms) were given to five normal, euthyroid subjects and eleven patients receiving long-term thyroxine-replacement medication. Blood samples were collected prior to and following ingestion of thyroxine. A significant increase in total thyroxine (T4), free thyroxine index (FTI) and free T4 (FT4) concentration was observed at all doses. No significant change was observed in 3,5,3'-triiodothyronine, 3,3',5'-triiodothyronine or thyrotrophin concentrations. Although T4, FTI and FT4 were significantly elevated 1 h after ingestion of all doses of thyroxine and remained elevated for at least 6 h, supranormal values were observed only after ingestion of the highest dose of thyroxine. The levels of T4, FTI and FT4 in patients receiving thyroxine should be interpreted in relation to the time of thyroxine administration. Standardisation of blood collection in patients receiving thyroxine replacement would be desirable.

Humans↗